Young's double slit experment is first performed in air and then in a medium other than air. It is found that 8th bright fringe in the medium lies where 5th dark fringe lies in air. The refractive index of the medium is nearly :

Question

Young's double slit experment is first performed in air and then in a medium other than air. It is found that 8th bright fringe in the medium lies where 5th dark fringe lies in air. The refractive index of the medium is nearly : (A) 1.59 (B) 1.69 (C) 1.78 (D) 1.25

Tardigrade Admin · Accepted Answer

(y8) Bright, medium = (y5) Dark, air (8 λm D/d) = ( (2 (5) - 1/2) ) (λ D/d) (8 λ/μ) (D/d) = (9/2) (λ D/d) ⇒ μ = (16/9) = 1.78

Q. Young's double slit experment is first performed in air and then in a medium other than air. It is found that $8 t h$ bright fringe in the medium lies where $5 t h$ dark fringe lies in air. The refractive index of the medium is nearly :

1.59

1.69

1.78

1.25

$(y_{8})$ Bright, medium = $(y_{5})$ Dark, air
$\frac{8 λ _{m} D}{d} = (\frac{2 ( 5 ) - 1}{2}) \frac{λ D}{d}$
$\frac{8 λ}{μ} \frac{D}{d} = \frac{9}{2} \frac{λ D}{d}$
$\Rightarrow μ = \frac{16}{9} = 1.78$

Q. Young's double slit experment is first performed in air and then in a medium other than air. It is found that 8th bright fringe in the medium lies where 5th dark fringe lies in air. The refractive index of the medium is nearly :